No abstract

O conhecimento das propriedades físicas do solo e o potencial das culturas denominadas “recuperadoras” de estrutura é importante para as tomadas de decisão sobre o manejo agrícola, assim, o estudo envolvendo plantas de cobertura, são importantes quando se objetiva a sustentabilidade dos cultivos. Desta forma, o presente trabalho teve como objetivo avaliar o impacto do cultivo de plantas de cobertura na estrutura de um Latossolo argilosos sob sistema plantio direto e os seus reflexos no rendimento de grãos de milho.  Os tratamentos foram constituídos por seis espécies de cobertura de inverno: aveia branca, aveia preta, centeio, aveia preta + nabo forrageiro, aveia preta + tremoço branco, aveia preta + ervilha, além do sistema de plantio direto tradicional (testemunha). O delineamento experimental foi inteiramente casualizado com 4 repetições em parcelas experimentais de 20x16 m. Foram coletadas amostras indeformadas de solo nas camadas de 0,00-0,10 m, 0,1-0,20 m e 0,20-0,30 m, após dessecação das espécies de cobertura e após a colheita do milho, sobre as quais implantou-se a cultura do milho.  O rendimento de grãos de milho foi avaliado com 3 repetições, em área de 13,5 m², e a umidade dos grãos foi corrigida a 13%. As médias dos tratamentos foram comparadas pelo teste Tukey a 5% de significância, com a utilização do programa Sisvar. As espécies de cobertura que apresentaram maior eficiência na reestruturação do solo foram os consórcios aveia preta + tremoço branco e aveia preta + ervilha forrageira. Quanto ao rendimento de grãos de milho, a aveia branca foi o tratamento que proporcionou o maior rendimento de grãos de milho, não diferindo dos tratamentos centeio, aveia preta + nabo, aveia preta + tremoço branco e do sistema plantio direto tradicional, evidenciando às boas condições de solo e clima da área experimental.

This study aimed to assess the potential of twelve cover crops in improving the structural state of the soil evaluating soil bulk density and soil resistance to penetration and their effects on crambe grain yield and oil content. The experiment was conducted at the Experimental Center of Agricultural Engineering (NEEA), at the State University of West Paraná (UNIOESTE)-Cascavel-Paraná. The cover crops were named as treatments and consisted of twelve species, namely: Crotalaria juncea, Crotalaria spectabilis, Pigeon pea, Jack bean, Foxtail millet, Forage sorghum, Lablab beans, Guandu beans, Mucuna aterrimum, Mucuna Pruriens, Mucuna deeringiana, Mucuna aterrima, and a control treatment (fallow area). The experimental design used consisted of randomized blocks with four replications and plots measuring 5 x 5 m. When species were in full bloom in May 2010, they were managed by desiccation with non-selective herbicide and subsequent mowing in order to accelerate the decomposition rate of their roots. In August 2011 we performed the planting of crambe for further analysis of its grain and oil yield. In January 2012 soil samples were collected to evaluate soil bulk density by the volumetric ring method at depths of 0.0-0.1, 0.1-0.2 and 0.2-0.3 m. Soil resistance to penetration was determined using a penetrometer until 0.4 m deep. In order to determine crambe grain yield, crambe was collected in an area of 4 m 2 in the central part of each plot. In ordet tor determe seed oil content it was used the Soxhlet method. The statistical analyzes for soil variables (soil penetration density and resistance) and plant (grain yield and oil yield) consisted of analysis of variance (ANOVA), with a comparison test of mean values. It was also performed linear regression analyzes between data concerning to grain yield and oil yield, as well as grain yield and bulk density. The species Crotalaria spectabilis and Mucuna aterrima provided a significant reduction in soil bulk density when compared to the fallow area, showing higher structuring potential than other species after the first year of use. Considering the structural state of the soil prior to the experiment, with bulk density values lower than 1.2 Mg m-3 , there was no significant effect on soil structure by any of the coverage species used and there was also no beneficial effect on crambe grain yield and oil content.

No abstract

The intense agricultural machinery traffic over the plantation ground can lead the erosion and growth difficulty. The goal of this study was to evaluate the soya bean yield after the implantation of species named “recoverable”, of soil structure. The experiment was developed in plots of 20 m × 25 m, located in the Agronomic Institute of Parana (IAPAR), in Santa Tereza do Oeste, Paraná. The plots were cultivated by direct sowing of the following species, considered as treatments: sunn hemp (Crotalaria juncea), rattlebox (Crotalaria spectabilis), velvet bean (Mucuna aterrima), pearl millet (Pennisetum glaucum), pigeon pea (Cajanus cajan), dwarf pigeon pea (Cajanus cajan) beside them no-tillage and no-cover crop planting traditional system (control). Soil samples were collected from 0-10 cm, 10-20 cm, and 20-30 cm-layers with 4 repetitions on each treatment. Soil density and porous soil space were also determined. The plot yield of soybean grains was evaluated over an area of 4.5 m2 for each treatment and grain moisture corrected to 13%. The treatments’ mean yields were compared using the Tukey test at 5% probability. The dwarf pigeon pea and the rattlebox were the most efficient cover crops in the reduction of soil bulk density in 0-10 and 10-20 cm depths. The soybean grain yield did not differ between the evaluated treatments, possibly due to the good precipitation conditions during the soybean growing cycle.